Control algorithms for out‐of‐chain routing in a telephone network
Akira Fukuda · Electronics and Communications in Japan (Part I Communications) · 1984
Abstract When part of a telephone network is congested because a different traffic pattern from that designed is offered, attempts are made to improve the network throughput by utilizing other vacant facilities. One such control method is out‐of‐chain routing, which permits calls which overflow from the final in‐chain route under the existing routing scheme (far to near rotation) to be offered to out‐of‐chain routes. Out‐of‐chain routing is expected to improve the network throughput but, on the contrary, it could degrade the network throughput by increasing the traffic toward the alternate route. Therefore a control algorithm for out‐of‐chain routing becomes necessary. This paper first models the switching machine which affects the network overload performance and clarifies the traffic characteristics of three‐node triangle network model when out‐of‐chain routing is permitted unconditionally. As a result, it is clarified that the algorithm which stops routing to the out‐of‐chain routes with office congestion is important. Also, the algorithm which permits out‐of‐chain routing when there is no trunk congestion on out‐of‐chain routes may decrease the throughput compared with the case of no out‐of‐chain routing. the results presented here are confirmed by computer simulation of a laeger network.